61 lines
1.9 KiB
C
61 lines
1.9 KiB
C
#include<stdlib.h>
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#include<stdio.h>
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#include<math.h>
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int p[512];
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double fade(double t) { return t * t * t * (t * (t * 6 - 15) + 10); }
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double lerp(double t, double a, double b) { return a + t * (b - a); }
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double grad(int hash, double x, double y, double z) {
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int h = hash & 15;
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double u = h<8 ? x : y,
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v = h<4 ? y : h==12||h==14 ? x : z;
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return ((h&1) == 0 ? u : -u) + ((h&2) == 0 ? v : -v);
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}
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double noise(double x, double y, double z) {
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int X = (int)floor(x) & 255,
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Y = (int)floor(y) & 255,
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Z = (int)floor(z) & 255;
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x -= floor(x);
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y -= floor(y);
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z -= floor(z);
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double u = fade(x),
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v = fade(y),
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w = fade(z);
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int A = p[X ]+Y, AA = p[A]+Z, AB = p[A+1]+Z,
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B = p[X+1]+Y, BA = p[B]+Z, BB = p[B+1]+Z;
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return lerp(w, lerp(v, lerp(u, grad(p[AA ], x , y , z ),
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grad(p[BA ], x-1, y , z )),
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lerp(u, grad(p[AB ], x , y-1, z ),
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grad(p[BB ], x-1, y-1, z ))),
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lerp(v, lerp(u, grad(p[AA+1], x , y , z-1 ),
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grad(p[BA+1], x-1, y , z-1 )),
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lerp(u, grad(p[AB+1], x , y-1, z-1 ),
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grad(p[BB+1], x-1, y-1, z-1 ))));
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}
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void loadPermutation(char* fileName){
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FILE* fp = fopen(fileName,"r");
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int permutation[256],i;
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for(i=0;i<256;i++)
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fscanf(fp,"%d",&permutation[i]);
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fclose(fp);
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for (int i=0; i < 256 ; i++) p[256+i] = p[i] = permutation[i];
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}
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int main(int argC,char* argV[])
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{
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if(argC!=5)
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printf("Usage : %s <permutation data file> <x,y,z co-ordinates separated by space>");
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else{
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loadPermutation(argV[1]);
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printf("Perlin Noise for (%s,%s,%s) is %.17lf",argV[2],argV[3],argV[4],noise(strtod(argV[2],NULL),strtod(argV[3],NULL),strtod(argV[4],NULL)));
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}
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return 0;
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}
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